Snap action switch with low force differential

ABSTRACT

Single-pole double-throw snap action switch device has a rocking element which pivots at one end on a fixed terminal element and at its opposite end pivotally supports a movable contact element in a V-shaped pocket. An actuator member, which can be either rigid or flexible, is mounted to apply an actuating force to the rocking element intermediate its two ends. The actuating member and the rocking element contact each other in a rolling, nonsliding motion which is substantially frictionless. The device also has a mount for an overcenter spring which eliminates any possibility of shifting of the spring&#39;&#39;s fixed pivot. This mount comprises a bent apertured tab to which the spring is attached. The aperture in the tab is chamfered on one side of the tab to insure the spring end can only contact the edge of the aperture on the unchamfered side.

United States Patent [72] Inventor Phillip M. Elliott 3,349,202 10/1967Beer 200/67B(UX) Schiller Park, Ill. 3,407,276 10/1968 Pescetto200/67B(UX) [2H P L427 Primary Examiner-David Smith,ir. [22] FlledJuly11968 Att0rneyRobertW.Beart, Michael l(ovac,Barry L.Clark [45]Patented Feb. 23,1971 and Jack Halvorsen [73] Assignee Illinois ToolWorks Inc.

Chicago, Ill.

ABSTRACT: Single-pole double-throw snap action switch device has arocking element which ivots at one end on a [54] SNAP ACTION SWITCH WITHLOW FORCE fixed terminal element and at its opp site end pivotally supDIFFFRENTIAI1 ports a movable contact element in a V-shaped pocket. Anac- 8 clalmss Drawmg tuator member, which can be either rigid orflexible, is [52] US. Cl 200/67 mounted to apply an actuating force tothe rocking element [51] Int. Cl ..H0lh 13/28 intermediate its two ends.The actuating member and the [50] Field ofSearch 200/67, rocking elementcontact each other in a rolling, nonsliding 67(B) motion which issubstantially frictionless. The device also has a mount for anovercenter spring which eliminates any possi- References Cited bility ofshifting of the springs fixed pivot. This mount com- UNITED STATESPATENTS prises a bent apertured tab to which the spring is attached.2,800,546 7/1957 Reitler 200/67B(UX) The aperture in the tab ischamfered on one Side of the tab to 3,030,465 4/1962 Reese. 2O0/67B(UX)insure the spring end can only contact the edge of the aperture3,114,805 12/1963 Baumer 200/67B(UX) on the uhchamfered SldeHHHH|HHHHIHHlHHHHHIHVJHH[iii]IHHHHHHHHHHHHHHIHHH" BACKGROUND OF THEINVENTION 1. Field of the lnvention This invention relates to snapaction switch devices and more particularly, to improved actuatingstructure therefor which permits a low movement differential and a lowforce differential for a given degree of contact pressure.

2. Description of the Prior Art 1 Single-pole double-throw snap actionswitch devices are well known in the prior art. One particular prior artdevice which is generally similar to the device described herein is thatshown in U.S. Pat. application Ser. No. 596,515, filed Nov. 23, 1966,now US. Pat. 3,407,276 and assigned to the' same assignee as the presentapplication.

In the selection of a switch for a given purpose, factors which areusually of great importance include: (a) the amount of force required toactuate the switchthe operating force; (b) the amount of spring forcestored in the switch after actuation which is available to reset theswitch-the release force; (c) the amount of movement of the actuatorbutton between the point at which the switch snaps in one direction andin the opposite direction-the movement differential; and (d) the contactpressure. Although the movement differential can be made quite low bymoving the fixed support for the overcenter coil spring to a positionvery close to the movable pivot point for the movable contact blade,such a mounting will necessarily alter the force vectors of the switchelements and reduce the pressure of the contacts. To achieve a desiredhigher contact pressure, it is then necessary to increase the springtension. However, since increased spring forces result in higheroperating forces and greater friction losses due to parts bending and/orsliding in contact with each other, the amount of energy which isavailable for resetting the switch after actuation does not increase atthe same rate as the increase in operating force. Thus, the forcedifferential, which is the difference between the operating and releaseforces increases and presents a situation where the release forceavailable becomes undesirably low.

The switch device shown and described in the aforementioned copendingapplication includes an actuator button movable vertically within a setof guides. The flat bottom surface of the actuator button is engagedwith a generally flat end surface of a pivoted rocking element which inturn pivotally mounts the movable blade. Since the flat end of therocking element slides transversely across the end of the actuatorbutton during actuation of the button, it will be understood that notonly will sliding friction be produced between the flat end of therocking element and the bottom of the button, but the sideways movementof the end of the rocking element as it is being actuated will produce asideways force on the pushbutton which will move it against one or theother of its side guides depending upon whether the button is depressedor released. Although these frictional losses are fairly small, they aresignificant. Another source of slight frictional loss in the device ofthe aforementioned application arises from its provision of a smallradius pin member for supporting one end of the overcenter coil springwhich biases the movable contact member. Although, during actuation, thecoil spring pivots only a few degrees, there are, nevertheless, frictionlosses produced as the spring tends to rotate around the pin.

By reducing the already low friction losses inherent in the prior artdesign with the structure disclosed herein, tests have shown that theforce differential of the prior art switch can be improved by more than100 percent. For example, one model of a switch made in accordance withthe teachings of the aforementioned application has an operating forceof 24 grams and a release force of 12 grams. However, by using theimproved construction of the present invention, a similar switch hasbeen built which has the same operating force of 24 grams but a releaseforce of 19 grams and higher contact pressures. Since the forcedifferential equals the difference between the operating force and therelease force, it will be readily seen that the improved design has aforce differential of a mere 5 grams while the prior design has a forcedif ferential of 12 grams. Other tests have shown that by changing theangle at which the actuating force is applied, from that disclosed inthe aforementioned application, it is possible to increase the verticalforce component which is available for resetting the switch aftertripping from 25 percent of stored spring energy to nearly 46 percent.

SUMMARY It is an object of this invention to provide a single-poledouble-throw snap action switch which has less frictional losses duringactuation than prior art devices, that requires less force to operate itfor a given movement differential or contact pressure, that retains agreater release force to reset itself, that can utilize parts having arelatively large tolerance variation, that is easy to assemble, thatprovides a good wiping action, and that is economical.

Another object of this invention is to provide a single-poledouble-throw snap action switch which can have certain partspreassembled before they are mounted in the switch case and which can betested iwhilein the switch case before the cover is applied thereto.

These objects are obtained by the switch device of the present inventionwhich preferably comprises a housing enclosing a plurality of terminals.One of these terminals, a common terminal, has a rocking element pivotedto it and carries a spring means which holds a movable contact elementin pivotable contact with the rocking element. Also mounted in theswitch case is an actuator member which may be either rigid or flexible.The actuator member is normally held in biased engagement with a portionof the rocking element positioned intermediate the pivoted end of therocking element and the portion which supports the movable contactmember. The actuator member has an actuating portion on its tip whichpresents a small radius in rolling contact with a groove in the rockingelement. The actuator member and the rocking element are mountedrelative to each other so that the actuating force is applied generallyin a direction perpendicular to a line between the pivoted end of therocking element and the line of contact with the actuating member.During actuation, the movement between the actuator member and therocking element appears to be a generally pivotal line to line contactbut is actually a slight rolling contact due to the slight radii of theparts. Although, theoretically, the actuator could have a line contactat its tip, sucha tip would easily break. A rounded tip is far strongerand wears much longer.

The overcenter coil spring used in the switch is mounted at one end toan aperture in the movable contact blade and at the other end to anapertured tab portion formed out of the material of the common terminalelement. The apertured tab portion is bent upwardly at a slight anglerelative to the axis of the overcenter spring. This bending of the taband a chamfering of the lower edge of the hole in the tab through whichthe spring passes causes the spring end to pivot on a sharp edge. Such amounting not only reduces the friction losses inherent in a designwherein the spring end must pivot about a pin but eliminates the shiftin the pivot point which could take place if the spring end were mountedin an unchamfered hole. By preventing the possibility of the pivot pointshifting, the move ment differential can be made very low without anychance of the switch failing to snap or of the moving contact floatingbetween the fixed contacts.

Another area in which my switch device has improved efficiency, and thusa lower force differential, is in its mounting of a spring lever foroperating the actuator member when the switch is assembled to beactuated by an offcenter button and lever system. By mounting the springlever for movement about a fixed fulcrum point, little of the energyimparted to the spring lever during actuation is lost in the way offriction. Furthermore, since the switch housing includes only two points(one of which is the fulcrum) which must bear on the spring lever at itsmounting end, the spring lever can be bent during manufacture within arather large tolerance range without affecting its operatingcharacteristics.

The foregoing and other objects, features and advantages will beapparent from the following more particular description of preferredembodiments thereof, as illustrated in the accompanying drawings.

BRIEF DESCRIPTiON OF THE DRAWINGS FlG. l is a top plan view of theswitch device of the present invention shown in its normal condition andwith its cover DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, myimproved switch device is shown in its normal, unactuated position. Theswitch mechanism is enclosed within a case housing indicated generallyat which includes outer upwardly extending wall surfaces 12 having holes14 therein for mounting the switch. Spaced slightly inwardly of theexterior walls 12 are interior walls l6 which are recessed below theheight of exterior walls 12 by the thickness of a cover plate (notshown) which is mounted over the central portion of the switch and heldthereto by fastening means (not shown) which extend into the covermounting holes 18. The elements of the switch device are mountedinteriorly of the interior walls 16 in a recessed area 20. The interiorrecessed portion 20 communicates with the outside of the switch case bymeans of a plurality of slots into which are placed an upper fixedterminal element 24, a lower fixed terminal element 26, and a commonfixed terminal element 28. The upper and lower fixed terminal elements24, 2e are held in place at their opposite ends in the inside of thecase by molded formations in the case including a pair of retainingstuds 30. The centrally located fixed common terminal element 28includes the bent arm portion 32 receivable in a slot 34 in the switchcase.

The switch mechanism is actuated by an actuator member 36 having anactuating tip portion 38 of small radius. The actuator 36 is guided forreciprocal sliding movement within the case by means of a pair of shortintegral guide pins 40 and a pair of longer guide members 42, d3. Theactuator is preferably molded of plastic and includes a slot 44 forclearing terminal 24. A slot as clears the spring 72. The arrangement ofslots permits the actuator to be mounted in the case after the metalswitch parts have been assembled.

The fixed common terminal element 28 includes a bent pivot grooveportion 48 in which a first pivoted end portion 50 k of a rockingelement 52 is positioned. The rocking element 52 of the two leg portions54 and 56 is an actuating second portion as which is engaged by theactuating tip portion 38 of the actuator 36. As can be seen in comparingthe relative positions of the actuator tip portion 38 and the actuatingportion 66 in the normal and actuated positionsof the switch as shown inF265. 1 and 2., it will be obvious'that tip portion 38 has a rollingrather than a sliding action relative to actuating portion 60 due to therounded surfaces of contact and the fact that the movement of actuator35 is in a direction generally perpendicular to a line connectingactuating portion fill on rocking element 52 with the pivot portion 50of said rocking element. Since a sliding contact between elements 38 and60 would produce frictional losses in the switch and thus decrease itsefficiency and increase its force differential, it is highly desirablethat no sliding be permitted to take place between these elements.Although actuating tip portion 38 could be made very sharp so as toassure a line type pivot connection with portion 60 of rocking element52, such a sharp tip is undesirable for several reasons. For one thing,it is impossible to mold an absolutely sharp corner or to even maintaina fairly sharp corner during extended mold usage. Furthermore, a sharpcorner at tip 3% would be fairly weak and thus subject to rapid wearwhich would in turnalter the position'of actuator 36 during its movementat which switching takes place. Since it is extremely desirable that theactuator maintain its position at which switching takes place throughoutthe life of the switch, and since this particular switch has been shownto have a life of well in excess of 50 million cycles, it is preferablethat the tip portion 38 of the actuator 36 be slightly rounded to giveit strength and to permit it to roll without friction in contact withthe actuating regions 6% during actuation.

At the end of short leg portion 56 of the rocker element 52 which is theend of the rocking element opposite to the first end portion 50, is athird pivot portion which comprises a V groove 64 for receiving theknife edge 66 of a movable contact blade 68.

As seen in FIG. 3, the movable contact blade 63 is biased into contactwith the V groove 6d of rocking element 52 by means of an overcentercoil spring 72. One end 74 of the spring passes through an anchor hole76 in the movable contact blade. The opposite end 78 of the spring ismounted to a tab 80 formed integrally with the common fixed terminalelement 28. The tab 80 has an anchor hole 82 for receiving the end 78 ofthe spring. Referring to FIG. 4, it will be seen that the hole 82 is notof constant diameter but includes a chamfered enlarged portion 84 on thebottom of the tab 80. Due to the chamfered portion M as well as theangle at which the tab 80 is bent relative to the axis of the spring 72,it will be appreciated that movement of spring 72 in a counterclockwisedirection from its FIG. 1 to its FIG. 2. position will not result in anyshifting of the pivot point 85 of the end of spring 78 from the positionshown in FIG. 4 wherein it contacts the upper edge of the hole 82.Without the chamfer 84 and the angle of tab 80, it is possible that thepivot point of spring end 78 could shift during switch actuation fromthe point $5 shown in FIG. 4 to point 86. Obviously, if such a pivotshift could take place, it would greatly affect the operatingcharacteristics of the switch. For example, a shift in pivot positionwould result in additional friction losses and would increase theopportunity for the movable contact blade 68 to float rather than haveits upper movable contact 9t) in positive engagement with upper fixedcontact 92 or its lower movable contact 94 in engagement with lowerfixed contact 96.

Another significant advantage of my switch device is its ability towithstand extremely high acceleration forces. By limiting the outwardmovement of the movable blade 68 with a molded wall 97 and by limitingthe movement of the rocking element 52 with molded internal walls 98, 99these movable elements are trapped so that even if they should be jarredfrom their seats 64, d8 respectively, they will always return to them.In one test, these movable switch elements did not become detached evenafter being subjected to forces of 200 G's, although the plastic switchcase started to shear internally. By using stronger materials, theability of the switch to withstand high accelerations could be increasedeven further.

In order to permit the upper end tilt) of actuator 36 to be actuatedfrom the exterior of the case 10, a secondary spring lever actuatorsystem is provided. Although it is of course possible, and oftendesirable, to locate a pushbutton in the walls l2, 16 of the case whichis directly in line with the actuator 36, I have shown in FIG. 1 anoffcenter type of actuator system which utilizes a spring lever so thata much lower operating forcecan be applied to offcenter button 102 thenwould be required if button 102 were directly in line with actuator 36.As can be seen in FIG. 1, the offcenter actuator button 102 engages theright end We of a spring lever 106 which is mounted in the recessedportion of the case for pivotal movement about a fulcrum 108. Aprojection 112 formed in the case presses against a point 114 on thelever 106 and cooperates with the pressure applied at point 104 on theother endof lever 106 by pushbutton 102 to maintain the lever in contactwith fulcrum at all times. The lever 106 is preferably bent at end 118as shown in FIG. 1 so as to anchor it in recess 120 in the case. it willbe noted that the lever 106 has a radius in the region between pressurepoint 114 and fulcrum 108 which is greater than that of a boss portion122 in the case between the same points. This region of greater radiusinsures that the fulcrum point of the lever will not change during theactuating or return movement of end 104 of the lever. This mountingwherein the fulcrum does not shift is very desirable since it insuresthat a large percentage of the spring energy imparted to the lever 106during actuation will be transferred to the actuator 36 and most of theremaining energy will be available to reset the lever 106 and button 102during a return operation. Furthermore, the design insures that the leftend of the lever will not slidingly engage with boss 122. By restrictingthe movement of lever 106 to a pivoting movement about only a singlepoint, namely 108, there is no change in the lever arm length of lever106 and thus, the leverage ratio required to be exerted on the lever bythe button 102 remains constant, keeping the force differential at acontrolled minimum.

in FIG. 5, a modification of the actuator mechanism shown in FIG. 1 isshown. The modified design permits the switch mechanism to be actuatedby means of the rotary movement of an external operating lever. Themodified design is especially valuable for use in a coin operated switchsince it can be actuated with only a few grams of force. Themodification of FIG. 5 includes a very thin flexible spring fingeractuating member 36a having an actuating tip portion 380. Although theactuating member 360 is flexible, it has the same nonsliding rollingaction on the actuating portion 60a of the rocking element 520 as doesthe rigid actuating tip 38 of the actuator 36 in the embodiment shown inFIGS. 1-4. The flexible finger 36a has a bent end portion 1000 which ismounted around a rotary actuator support 124. A pair of integralpositioning ears 126 project from the actuator support 124 and preventrelative rotation of the actuator end 1000 relative to the actuatorsupport 124. A hearing shoulder 128 extends through the case forrotatably mounting the actuator support 124 to the case. An operatinglever 130 is mounted for movement with shoulder 128 and rotary actuatorsupportl24 and is attached thereto by means such as a hole or a slot.From the dotted lines showings of the various elements of the mechanismin their actuated position, it can be appreciated that only a smallrotational movement of operating lever 130 is required to cause theactuating tip portion 38a to pivot the rocking element 52a against astop portion 134 in the switch case. Once the rocking element 52a hascontacted the stop 134, continued overtravel rotation of the operatinglever will merely result in additional flexing of the flexible actuatingfinger 360. By means of appropriate stops (not shown) the rotationaltravel of rotary actuator support 124 is limited in order to insure thatthe actuator tip 380 does not become displaced from the actuating region60 and that the actuating finger 360 does not become bent beyond itselastic'limit.

Although my invention makes it possible to achieve a switch having avery low force differential, it should be recognized that there are raresituations where a switch having-a high force differential is required.For such situations, the various elements such as the springs and springmounting locations can be changed to achieve the desired results. Itshould be recognized that even though my switch can be made to havehigher force differentials, it would not follow that other switcheshaving high force differentials could be modified to have lower ones.

lclaim:

l. A single-pole double-throw snap action switch device comprising, aswitch housing having an actuator member mounted for movement from anormal to a second position, a

movable contact assembly engaged by said actuator member and including arocking element pivotally mounted at a first portion thereof to,a commonterminal element and having a second portion thereof positioned forengagement by said actuator member, a movable contact blade pivotallymounted at one end thereof to a third portion'of said rocking elementand carrying at its other end a contact element disposed between aspaced pair of fixed contact elements each being electrically connectedto a separate terminal element, said second portion of said rockingelement being located intermediate said first and third portions, springmeans fixed at one end within said switch housing and at its other endto said movable contact blade for normally biasing the contact elementof said movable contact blade against one of said fixed contact elementsand for yieldably urging said second portion of said rocking elementagainst said actuator member to hold said actuator member in its normalposition said actuator member including at least one actuator portionmovable in a rectilinear direction for engaging said second portion ofsaid rocking element throughout its range of movement in rolling,nonsliding, relationship, said actuator member being capable of beingactuated for movement to its second position causing substantiallysimultaneous pivotal movement of said rocking element and said movablecontact blade for overcoming the biasing effect of said spring means toprovide a wiping effect of the contact element on said movable contactblade as it is moved with a snap action between said fixed contacts,release of said actuator member causing return of the switch componentsto their normal position, said rolling, nonsliding relationship withsaid rocking element being retained throughout the range of movement ofsaid actuator member by the engagement of cooperating mating convex andconcave surfaces provided on the actuator portion of said actuatormember and the second portion of said rocking element with the radius ofcurvature of the convex surface provided on one of the actuator portionof said actuator member or the second portion of said rocking elementbeing less than the radius of curvature of the concave surface providedon the other of the actuator portion of said actuator member or thesecond portion of said rocking element.

2. The switch device as'defined in claim 1 wherein said actuator memberis disposed within'said switch body and is engaged by a spring leverfrictionally mounted near one of its ends for pivotal movement about afulcrum portion in a recess in said housing, said spring lever beingcontacted at its other end by a depressable plunger element extendingthrough the housing for engaging and causing pivotal movement of saidspring lever to move the actuator member between its normal and secondpositions, said spring lever being further contacted by a projection insaid recess at a point between said fulcrum and said one end, saidprojection being on the same side of said spring lever as said plungerelement, said frictional mounting pennitting a portion of the energytransferred to said spring lever by said depressable plunger when saidplunger is depressed to be stored in the portion of said spring leverbetween said fulcrum and said projection, said stored energy beingreturned to said spring lever to assist in the resetting of the switchwhen pressure on the plunger is released.

3. The switch device as defined in claim 1 wherein said spring meanscomprises a helical coil spring pivotally mounted at one end to anapertured portion of an angled arm on said common terminal element andhaving its other end mounted to said movable contact blade.

4. The switch device as defined in claim 3 wherein said angled arm ischamfered at one end of said apertured portion for preventing any shiftin the pivot support point for said coil spring during movement of saidactuator member from its normal to its second position.

5. The switch device as defined in claim 1 wherein said actuator membercomprises a pair of spaced legs extending in the direction of movementof said actuator member and defining a pair of actuator portions forengaging said rocking element, said actuator member further comprising anotched portion positioned substantially at a right angle to said legsand spaced therefrom, said notched portion cooperating with a notchformed in one of said fixed terminal elements to permit said actuatormember to be installed in said housing subsequent to the installation ofsaid notched fixed terminal element.

6. The switch device as defined in claim 1 wherein said rocking elementcomprises a piece of metal sheet material which is generally L-shapedand arranged in the switch housing with its short leg extending in thedirection of movement of said actuator member and adjacent thereto, saidshort leg being bent at said third portion to include a first V-shapedpocket for receiving the end of said movable contact blade, said rockingelement having a long leg arranged generally perpendicular to thedirection of movement 'of said actuator member and having a secondV-shaped pocket positioned at said second portion for receiving saidactuator portion, the free end of said long leg comprising said firstportion.

7. The switch device as defined in claim 6 and further including aplurality; of integral wall portions formed in said switch housingadapted to cooperate with said first and second V-shaped pockets toentrap said movable contact blade and said rocking element and preventthem from being permanently detached from said V-shaped pockets afterbeing subjected to high acceleration forces.

8. The switch device as defined in claim 1 wherein said actuator membercomprises a thin flexible spring finger member, the end of said springfinger member opposite said at least one actuator portion being mountedin said switch housing for rotational actuation by an operating leverpivotally mounted in said housing and connected thereto, said springfinger member being adapted to flex and bend between its ends when saidoperating lever is pivoted beyond the amount of movement necessary tocause said at least one actuator portion to pivot said rocking elementto its actuated position.

1. A single-pole double-throw snap action switch device comprising, aswitch housing having an actuator member mounted for movement from anormal to a second position, a movable contact assembly engaged by saidactuator member and including a rocking element pivotally mounted at afirst portion thereof to a common terminal element and having a secondportion thereof positioned for engagement by said actuator member, amovable contact blade pivotally mounted at one end thereof to a thirdportion of said rocking element and carrying at its other end a contactelement disposed between a spaced pair of fixed contact elements eachbeing electrically connected to a separate terminal element, said secondportion of said rocking element being located intermediate said firstand third portions, spring means fixed at one end within said switchhousing and at its other end to said movable contact blade for normallybiasing the contact element of said movable contact blade against one ofsaid fixed contact elements and for yieldably urging said second portionof said rocking element against said actuator member to hold saidactuator member in its normal position said actuator member including atleast one actuator portion movable in a rectilinear direction forengaging said second portion of said rocking element throughout itsrange of movement in rolling, nonsliding, relationship, said actuatormember being capable of being actuated for movement to its secondposition cAusing substantially simultaneous pivotal movement of saidrocking element and said movable contact blade for overcoming thebiasing effect of said spring means to provide a wiping effect of thecontact element on said movable contact blade as it is moved with a snapaction between said fixed contacts, release of said actuator membercausing return of the switch components to their normal position, saidrolling, nonsliding relationship with said rocking element beingretained throughout the range of movement of said actuator member by theengagement of cooperating mating convex and concave surfaces provided onthe actuator portion of said actuator member and the second portion ofsaid rocking element with the radius of curvature of the convex surfaceprovided on one of the actuator portion of said actuator member or thesecond portion of said rocking element being less than the radius ofcurvature of the concave surface provided on the other of the actuatorportion of said actuator member or the second portion of said rockingelement.
 2. The switch device as defined in claim 1 wherein saidactuator member is disposed within said switch body and is engaged by aspring lever frictionally mounted near one of its ends for pivotalmovement about a fulcrum portion in a recess in said housing, saidspring lever being contacted at its other end by a depressable plungerelement extending through the housing for engaging and causing pivotalmovement of said spring lever to move the actuator member between itsnormal and second positions, said spring lever being further contactedby a projection in said recess at a point between said fulcrum and saidone end, said projection being on the same side of said spring lever assaid plunger element, said frictional mounting permitting a portion ofthe energy transferred to said spring lever by said depressable plungerwhen said plunger is depressed to be stored in the portion of saidspring lever between said fulcrum and said projection, said storedenergy being returned to said spring lever to assist in the resetting ofthe switch when pressure on the plunger is released.
 3. The switchdevice as defined in claim 1 wherein said spring means comprises ahelical coil spring pivotally mounted at one end to an apertured portionof an angled arm on said common terminal element and having its otherend mounted to said movable contact blade.
 4. The switch device asdefined in claim 3 wherein said angled arm is chamfered at one end ofsaid apertured portion for preventing any shift in the pivot supportpoint for said coil spring during movement of said actuator member fromits normal to its second position.
 5. The switch device as defined inclaim 1 wherein said actuator member comprises a pair of spaced legsextending in the direction of movement of said actuator member anddefining a pair of actuator portions for engaging said rocking element,said actuator member further comprising a notched portion positionedsubstantially at a right angle to said legs and spaced therefrom, saidnotched portion cooperating with a notch formed in one of said fixedterminal elements to permit said actuator member to be installed in saidhousing subsequent to the installation of said notched fixed terminalelement.
 6. The switch device as defined in claim 1 wherein said rockingelement comprises a piece of metal sheet material which is generallyL-shaped and arranged in the switch housing with its short leg extendingin the direction of movement of said actuator member and adjacentthereto, said short leg being bent at said third portion to include afirst V-shaped pocket for receiving the end of said movable contactblade, said rocking element having a long leg arranged generallyperpendicular to the direction of movement of said actuator member andhaving a second V-shaped pocket positioned at said second portion forreceiving said actuator portion, the free end of said long legcomprising said first portion.
 7. The switch device as Defined in claim6 and further including a plurality of integral wall portions formed insaid switch housing adapted to cooperate with said first and secondV-shaped pockets to entrap said movable contact blade and said rockingelement and prevent them from being permanently detached from saidV-shaped pockets after being subjected to high acceleration forces. 8.The switch device as defined in claim 1 wherein said actuator membercomprises a thin flexible spring finger member, the end of said springfinger member opposite said at least one actuator portion being mountedin said switch housing for rotational actuation by an operating leverpivotally mounted in said housing and connected thereto, said springfinger member being adapted to flex and bend between its ends when saidoperating lever is pivoted beyond the amount of movement necessary tocause said at least one actuator portion to pivot said rocking elementto its actuated position.